scholarly journals Structural tailoring of hierarchical fibrous composite membranes to balance mass transfer and heat transfer for state-of-the-art desalination performance in membrane distillation

2019 ◽  
Vol 7 (5) ◽  
pp. 2376-2384 ◽  
Author(s):  
Xiaochan An ◽  
Guorong Xu ◽  
Baolei Xie ◽  
Yunxia Hu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
State Of The Art ◽  
Fibrous Composite ◽  
Composite Membranes ◽  
Membrane Distillation ◽  
Seawater Desalination ◽  
Wastewater Recycling

Membrane distillation (MD) displays superior characteristics to other technologies to alleviate the ever-increasing freshwater crisis through seawater desalination and/or wastewater recycling.

scholarly journals A novel internal heat recycling concept for reducing energy consumption and increasing flux through three-stage air-gap–water-gap membrane distillation system

2020 ◽  
Vol 20 (7) ◽  
pp. 2858-2874
Author(s):  
Mostafa Abd El-Rady Abu-Zeid ◽  
Xiaolong Lu ◽  
Shaozhe Zhang
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Energy Consumption ◽  
Heat And Mass Transfer ◽  
Waste Heat ◽  
Internal Heat ◽  
High Energy ◽  
Membrane Distillation ◽  
Air Gap ◽  
Air Gap Membrane Distillation

Abstract The low flux and high energy consumption problems of the conventional three-stage air-gap membrane distillation (AG-AG-AG)MD system caused by the low temperature difference between hot and cold feed at both sides of the membrane and high boundary layer thickness were solved successfully by replacing one of the three stages of air gaps by a water gap. The novel three-stage air-gap–water-gap membrane distillation (AG-AG-WG)MD system reduced energy consumption and increased flux due to efficient internal heat recycling by virtue of a water-gap module. Heat and mass transfer in novel and conventional three-stage systems were analyzed theoretically. Under a feed temperature of 45 °C, flow rate of 20 l/h, cooling temperature of 20 °C, and concentration of 340 ppm, the (AG-AG-WG)MD promoted flux by 17.59% and 211.69%, and gained output ratio (GOR) by 60.57% and 204.33% compared with two-stage (AG-WG)MD and one-stage AGMD, respectively. This work demonstrated the important role of a water gap in changing the heat and mass transfer where convection heat transfer across the water gap is faster by 24.17 times than conduction heat transfer through the air gap. The increase in flux and GOR economized the heating energy and decreased waste heat input into the system. Additionally, the number of MD stages could increase the achieving of a high flux with operation stability.

scholarly journals Research Progress in Computational Fluid Dynamics Simulations of Membrane Distillation Processes: A Review

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 513
Author(s):  
Long Chen ◽  
Binxin Wu
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Mass Transfer ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Membrane Distillation ◽  
Cfd Simulations ◽  
Membrane Pores ◽  
Characteristics Analysis ◽  
Physical Phenomena

Membrane distillation (MD) can be used in drinking water treatment, such as seawater desalination, ultra-pure water production, chemical substances concentration, removal or recovery of volatile solutes in an aqueous solution, concentration of fruit juice or liquid food, and wastewater treatment. However, there is still much work to do to determine appropriate industrial implementation. MD processes refer to thermally driven transport of vapor through non-wetted porous hydrophobic membranes, which use the vapor pressure difference between the two sides of the membrane pores as the driving force. Recently, computational fluid dynamics (CFD) simulation has been widely used in MD process analysis, such as MD mechanism and characteristics analysis, membrane module development, preparing novel membranes, etc. A series of related research results have been achieved, including the solutions of temperature/concentration polarization and permeate flux enhancement. In this article, the research of CFD applications in MD progress is reviewed, including the applications of CFD in the mechanism and characteristics analysis of different MD structures, in the design and optimization of membrane modules, and in the preparation and characteristics analysis of novel membranes. The physical phenomena and geometric structures have been greatly simplified in most CFD simulations of MD processes, so there still is much work to do in this field in the future. A great deal of attention has been paid to the hydrodynamics and heat transfer in the channels of MD modules, as well as the optimization of these modules. However, the study of momentum transfer, heat, and mass transfer mechanisms in membrane pores is rarely involved. These projects should be combined with mass transfer, heat transfer and momentum transfer for more comprehensive and in-depth research. In most CFD simulations of MD processes, some physical phenomena, such as surface diffusion, which occur on the membrane surface and have an important guiding significance for the preparation of novel membranes to be further studied, are also ignored. As a result, although CFD simulation has been widely used in MD process modeling already, there are still some problems remaining, which should be studied in the future. It can be predicted that more complex mechanisms, such as permeable wall conditions, fouling dynamics, and multiple ionic component diffusion, will be included in the CFD modeling of MD processes. Furthermore, users’ developed routines for MD processes will also be incorporated into the existing commercial or open source CFD software packages.

scholarly journals MEMBRANE DISTILLATION FOR SEAWATER DESALINATION APPLICATIONS IN VIETNAM: POTENTIAL AND CHALLENGES

2017 ◽  
Vol 55 (6) ◽  
pp. 659
Author(s):  
Hung Cong Duong ◽  
Nhan Duc Phan ◽  
Tinh Van Nguyen ◽  
Thao Manh Pham ◽  
Nguyen Cong Nguyen
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Fresh Water ◽  
Water Scarcity ◽  
Membrane Distillation ◽  
Practical Approach ◽  
Membrane Properties ◽  
Seawater Desalination ◽  
Comprehensive Review ◽  
Transfer Mechanisms

Desalination of seawater using membrane distillation (MD) can be a practical approach to mitigating the fresh water scarcity in Vietnam. This paper provides a comprehensive review of the seawater MD desalination process. The fundamentals of the MD process including configurations, membrane modules, membrane properties, and heat and mass transfer mechanisms together with approaches to enhancing heat and mass transfer are first systematically reviewed and analyzed. Then, the potential and challenges of the seawater MD desalination process are thoroughly discussed.

Heat and Mass Transport in HDP-CVD Chamber

2003 ◽  
Author(s):  
Hemant Mungekar ◽  
Bruno Geoffrion ◽  
Bikram Kapoor ◽  
Naren Dubey ◽  
Mak Salimian ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Aspect Ratio ◽  
State Of The Art ◽  
Memory Device ◽  
Device Fabrication ◽  
Shallow Trench Isolation ◽  
Heat And Mass Transport ◽  
Trench Isolation ◽  
Plasma Facing Materials

HDP-CVD reactors are used for Shallow Trench Isolation (STI), Inter Metal Dielectric (IMD) and Inter Layer Dielectric (ILD) applications for logic and memory device fabrication. As device dimension shrinks, the trend has been to use lower pressure and higher plasma density for gap-fill with higher aspect ratio (AR). Higher AR gapfill in addition to higher throughput is achieved by running multiple wafers between a chamber clean, present a unique set of challenges for heat and mass-transfer in an HDP-CVD reactor. This paper describes some of the new state-of-the-art hardware innovations specifically developed to meet these challenges. In particular, heat transfer to plasma facing materials, fluid mechanics, and transport of sub-micron sized particles in the plasma environment of an HDP-CVD reactor are explored.

Sign in / Sign up

Export Citation Format

Share Document